Variety V[871]
The variety generated by [6, 871]: all semigroups that satisfy every identity of [6, 871]. 4 semigroups of order six generate it, and 2,788 semigroups of order six lie in it.
Shortest known basis
3 identities irredundant
- xyx ≈ yxy
- xyz ≈ xzy
- xyzt ≈ uvws
Irredundant: none of these identities follows from the others; for each, a semigroup satisfies the others but not it. Obtained from a certified basis by removing identities that follow from the others (Vampire). Shortest known, not known to be minimal.
Certified bases
- 6 identities, certified in Lean for 4 semigroups
Among the 505 varieties
- Directly above
- Directly below
A variety lies above another when it contains it. An inclusion holds when the basis of the smaller variety derives that of the larger one, proved by Vampire; it fails when a semigroup of order six lies in the one and not in the other.
Explore V[871] in the inclusion graph, with everything above and below it.
Generated by 4 semigroups of order six
Contains 2,788 semigroups of order six
The semigroups of order six that satisfy the basis.